Accurately model RAM and ROM configurations

[frno7]

The read-only memory (ROM) and random-access memory (RAM) configurations vary between different models of PlayStation 2 hardware. A single, simplified, configuration is currently used for all models:

linux/arch/mips/ps2/memory.c

Lines 41 to 43 in 59a11ab

	add_memory_region(0x00000000, 0x02000000, BOOT_MEM_RAM);
	add_memory_region(ROM0_BASE, ROM0_SIZE, BOOT_MEM_ROM_DATA);
	add_memory_region(ROM1_BASE, ROM1_SIZE, BOOT_MEM_ROM_DATA);

See #28 (comment) for additional details.

[AKuHAK]

This issue comment and this comment should probably be moved here.

[AKuHAK]

Also few notes about EE RAM

linux/arch/mips/ps2/memory.c

Line 41 in 59a11ab

add_memory_region(0x00000000, 0x02000000, BOOT_MEM_RAM);

Here 0x02000000 represents available EE RAM (32Mb). Just would like to mention that this is also not a fixed value. PSX DESR can operate 64Mb of RAM and PS2Tool can operate 128Mb of RAM.
Part of this code is represented here:
https://gitlab.com/ps2max/linux/linux-2.2.1/-/blob/master/arch/mips/ps2/sbios/init.c#L38-L43

#ifdef CONFIG_T10000_MAXMEM
	ps2_bootinfox.maxmem = 128;
#else /* CONFIG_T10000_MAXMEM */
	ps2_bootinfox.maxmem = 32;
#endif /* !CONFIG_T10000_MAXMEM */
	ps2_bootinfox.maxmem = ps2_bootinfox.maxmem * 1024 * 1024 - 4096;

Here maximum RAM is defined in config, but it is possible to determine console type by proceeding with some commands.

Also, I noticed that last 4096 bytes of RAM is not usable for some reason, so probably you should map 0x02000000 - 0x10000 = 0x01FFF000